There are various nozzle design options to seal between the manifold and the nozzle -

(1) the solid skirt design with no active leakage prevention feature;

  (2) a nozzle that is bolted from the back to the manifold. High temperature screws are used to bolt the nozzle to the manifold and provide a positive seal in cold conditions. However, the system still requires a cold clearance since the solid skirt of the nozzle requires room to expand at operating temperature. While this approach provides a positive seal from nozzle to manifold it does not protect the components from thermal expansion due to overheating;

  (3) a nozzle, which is screwed into the manifold, moves with the expanding manifold. There are restrictions for minimum nozzle length and large pitch spacing with this design. This option is a simple and cost-effective way to provide a positive seal between nozzle and manifold for low cavitation systems; and (4) a nozzle with a spring design instead of a solid skirt. The spring provides preload in the cold condition and also prevents the system from damage if accidentally over-heated, by absorbing any thermal expansion. This allows a wide operating window of up to +/-200Fx.                

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